CN113573858A

CN113573858A - Gripping system and gripping method

Info

Publication number: CN113573858A
Application number: CN202080021129.4A
Authority: CN
Inventors: 松尾芳一; 胜又悠喜
Original assignee: THK Co Ltd
Current assignee: THK Co Ltd
Priority date: 2019-03-15
Filing date: 2020-03-16
Publication date: 2021-10-29
Anticipated expiration: 2040-03-16
Also published as: US11400589B2; JP6829738B2; DE112020001274T5; WO2020189619A1; JP2020146819A; CN113573858B; DE112020001274B4; US20220097229A1

Abstract

A gripping system provided with a robot mechanism stably grips a bag-shaped object in which a fluid is sealed. The method includes the steps of bringing a tip portion of a press-in finger portion of a robot mechanism into contact with a bag-shaped object to press-fit the bag-shaped object, bringing a pressure detected by a pressure detection portion provided in one of the press-in finger portions or a pressure detected by a pressure detection portion provided in each of the press-in finger portions into contact with the bag-shaped object, and then performing a gripping operation of gripping the bag-shaped object by at least two finger portions of a plurality of finger portions of the robot mechanism in a state where the press-in finger portion is pressed into the bag-shaped object.

Description

Gripping system and gripping method

Technical Field

The present invention relates to a gripping system and a gripping method for gripping an object with a plurality of fingers.

Background

Conventionally, a robot mechanism which is attached to a robot arm or the like and grips an object with a plurality of finger portions has been developed. For example, patent document 1 discloses a robot mechanism including three finger portions (fingers). In the robot mechanism of patent document 1, the three finger portions have the same configuration.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 2015-533669

Disclosure of Invention

Problems to be solved by the invention

In a gripping system including a robot mechanism for gripping an object with a plurality of fingers, a bag-shaped object in which a fluid (gas or liquid) is sealed may be the object. When such a bag-shaped object is pressed by a finger when being held by the robot mechanism, the shape of the object is likely to change. Therefore, friction is less likely to act than an object that is less likely to deform, and it may be difficult to maintain a state in which the bag-shaped object is sandwiched between a plurality of fingers.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of stably gripping a bag-shaped object in which a fluid is sealed in a gripping system including a manipulator mechanism for gripping the object by a plurality of fingers.

Means for solving the problems

A gripping system is provided with: a robot mechanism configured to grip an object with a plurality of finger portions; and a control device that controls the manipulator mechanism when the object is held, wherein, when the object is a bag-shaped object in which a fluid is sealed, at least one of the plurality of finger portions of the manipulator mechanism is a press-in finger portion, a pressure detection portion is provided at a tip portion of the finger portion of the manipulator mechanism that is the press-in finger portion, and when the object is the bag-shaped object, the control device brings the tip portion of the press-in finger portion of the manipulator mechanism into contact with the bag-shaped object to press-fit the bag-shaped object, and thereafter, after any one of a pressure detected by the pressure detection portion provided at the one press-in finger portion or a pressure detected by the pressure detection portion provided at each press-in finger portion reaches a predetermined pressure or more, the gripping operation is performed in a state where the pressing finger portion is pressed into the bag-shaped object, the bag-shaped object being sandwiched between at least two of the plurality of finger portions.

Effects of the invention

According to the present invention, a bag-shaped object in which a fluid is sealed can be stably gripped in a gripping system including a manipulator mechanism that grips an object by a plurality of fingers.

Drawings

Fig. 1 is a first diagram showing a schematic configuration of a gripping system according to an embodiment.

Fig. 2 is a second diagram showing a schematic configuration of the gripping system of the embodiment.

Fig. 3 is a perspective view of the robot mechanism of the embodiment.

Fig. 4 is a plan view of the robot mechanism of the embodiment.

Fig. 5 is a diagram showing the movable range of the second joint section in the finger section of the manipulator mechanism according to the embodiment.

Fig. 6 is a diagram showing a movable range of the first joint section in the finger section of the manipulator mechanism according to the embodiment.

Fig. 7 is a block diagram showing each functional unit included in the arm control device and the robot control device according to the embodiment.

Fig. 8 is a diagram showing the form of the robot mechanism when performing the pushing operation in embodiment 1.

Fig. 9 is a diagram showing a state of the robot mechanism and the bag-like object when the pushing operation is performed in example 1.

Fig. 10 is a diagram showing a robot mechanism and a bag-shaped object when a gripping operation is performed in example 1.

Fig. 11 is a flowchart showing a control flow of the gripping system in the case of performing gripping of the bag-like object according to embodiment 1.

Fig. 12 is a diagram for explaining the pushing operation and the gripping operation in example 2.

Detailed Description

The gripping system of the present invention includes: a robot mechanism for gripping an object with a plurality of finger parts, and a control device for controlling the robot mechanism.

In the gripping system of the present invention, the object gripped by the robot mechanism may be a bag-shaped object in which a fluid is sealed. Here, when a fluid such as a gas or a liquid is enclosed in the bag-shaped object, if the internal pressure of the bag-shaped object becomes high, the bag-shaped object is less likely to be deformed when an external force is applied. Therefore, when the internal pressure of the bag-shaped object is in a high state during a gripping operation, which is an operation of pinching the bag-shaped object with the finger portion of the robot mechanism, the bag-shaped object is less likely to be deformed when pressed with the finger portion during the gripping operation. As a result, the reaction force from the bag-shaped object against the finger portion that is inserted into the bag-shaped object becomes large. Therefore, the frictional force between the finger portion that sandwiches the bag-shaped object and the bag-shaped object can be increased.

Therefore, in the gripping system of the present invention, when the object is a bag-shaped object in which a fluid is sealed, at least one of the plurality of fingers of the manipulator mechanism is used for pushing. At this time, a pressure detection unit is provided at the tip of the finger portion serving as the press-in finger portion of the manipulator mechanism. Here, the pressure detection unit detects the pressure applied to the distal end portion of the finger portion.

Before the gripping operation by the robot mechanism is executed, the control device brings the distal end portion of the pushing finger portion of the robot mechanism into contact with the bag-shaped object and pushes the bag-shaped object (hereinafter, such an operation may be referred to as "pushing operation"). When this pushing operation is performed, the bag-shaped object is deformed, and the internal pressure thereof increases. Further, as the amount of press-fitting of the finger portion into the bag-like object during the press-fitting operation increases, the internal pressure of the bag-like object increases. Accordingly, the pressure detected by the pressure detection unit provided at the distal end of the press-fitting finger portion rises.

The control device starts the gripping operation after any one of the pressures detected by the pressure detection units provided in the respective pushing fingers reaches a predetermined pressure or more. At this time, the control device performs the gripping operation while maintaining the state in which the finger part for press-fitting is pressed into the bag-like object. Here, the predetermined pressure is a pressure capable of ensuring a sufficient frictional force for gripping between the finger portion of the manipulator mechanism and the bag-shaped object in order to apply a sufficient reaction force from the bag-shaped object to the finger portion when the bag-shaped object is sandwiched by the finger portion during the gripping operation.

As described above, according to the present invention, by performing the pushing operation before the gripping operation, the gripping operation can be performed in a state where the internal pressure of the bag-shaped object is sufficiently increased. Therefore, during the gripping operation, when the finger portion of the manipulator mechanism is pressed against the bag-shaped object, a sufficient frictional force can be secured between the finger portion and the bag-shaped object. Therefore, the bag-like object is easily maintained in a state of being sandwiched by the plurality of finger portions. As a result, the bag-like object can be stably gripped by the robot mechanism.

In the gripping system of the present invention, at least two fingers of the manipulator mechanism may be used as the pushing fingers. In this case, the pushing operation is performed in a state where the distance between the distal ends of the pushing fingers is not less than a predetermined distance. By performing the pushing operation by the plurality of pushing finger parts in this way, the amount of pushing of the bag-like object by the pushing finger parts when the internal pressure of the bag-like object is increased by the same degree can be made smaller than in the case of performing the pushing operation by one pushing finger part. In this way, the amount of pressing the bag-shaped object by the finger portion for pressing is reduced, and the damage of the content of the bag-shaped object caused by the pressing operation can be suppressed. Further, the amount of pressing the bag-like object by the pressing finger portion is reduced, and the time taken from the start of the pressing operation to the start of the gripping operation can be shortened. As a result, the tact time for gripping the bag-like object can be shortened.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in the present embodiment are not intended to limit the technical scope of the present invention to the above description unless otherwise specified.

< example 1 >

Fig. 1 and 2 are diagrams showing a schematic configuration of the gripping system according to the present embodiment. The gripping system 1 includes: a robot mechanism 2 for gripping an object 10, an arm mechanism 3, and a base unit 4. Here, the detailed configurations of the arm mechanism 3, the robot mechanism 2, and the base unit 4 in the gripping system 1 will be described.

(arm mechanism)

A robot mechanism 2 is attached to one end of the arm mechanism 3. The other end of the arm mechanism 3 is attached to the base unit 4. The arm mechanism 3 includes: a first arm link portion 31, a second arm link portion 32, a third arm link portion 33, a fourth arm link portion 34, a fifth arm link portion 35, and a connecting member 36. The base portion 20 of the manipulator mechanism 2 is connected to a first joint portion 30a formed on one end side of the first arm link portion 31 of the arm mechanism 3. The first joint section 30a is provided with a motor (not shown) for rotating the robot mechanism 2 with respect to the first arm link section 31 around the axis of the first arm link section 31. The other end side of the first arm link portion 31 is connected to one end side of the second arm link portion 32 via the second joint portion 30 b. The first arm link portion 31 and the second arm link portion 32 are connected in such a manner that their central axes intersect perpendicularly. The second joint section 30b is provided with a motor (not shown) for rotating the first arm link section 31 about the second arm link section 32 on the other end side with respect to the second arm link section 32 around the axis of the second arm link section 32. The other end side of the second arm link portion 32 is connected to one end side of the third arm link portion 33 via the third joint portion 30 c. A motor (not shown) for rotating the second arm link portion 32 relative to the third arm link portion 33 is provided in the third joint portion 30 c.

Similarly, the other end side of the third arm link portion 33 is connected to one end side of the fourth arm link portion 34 via the fourth joint portion 30 d. The other end side of the fourth arm link portion 34 is connected to the fifth arm link portion 35 via the fifth joint portion 30 e. A motor (not shown) for rotating the third arm link portion 33 relative to the fourth arm link portion 34 is provided in the fourth joint portion 30 d. The fifth joint section 30e is provided with a motor (not shown) for rotating the fourth arm link section 34 relative to the fifth arm link section 35. The fifth arm link portion 35 is connected to a connecting member 36 disposed perpendicularly to the base portion 4 via a sixth joint portion 30 f. The fifth arm link portion 35 and the connecting member 36 are connected so that their central axes are coaxial. A motor (not shown) for rotating the fifth arm link 35 about the axis of the fifth arm link 35 and the connecting member 36 is provided in the sixth joint 30 f. By configuring the arm mechanism 3 in this manner, the arm mechanism 3 can be configured to have a degree of freedom of 6 degrees of freedom, for example.

(mechanical arm mechanism)

Next, the structure of the robot mechanism 2 will be described with reference to fig. 3 to 6. Fig. 3 is a perspective view of the robot mechanism 2. Fig. 4 is a plan view of the robot mechanism 2. In fig. 4, arrows indicate the rotational movable ranges of the finger parts 21. The manipulator mechanism 2 includes: a base portion 20 connected to the arm mechanism 3, and four finger portions 21 provided on the base portion 20. As shown in fig. 3 and 4, in the robot mechanism 2, the four finger portions 21 are arranged at equal angular intervals (i.e., 90deg intervals) on the base portion 20 on a circumference centered on an axis in the longitudinal direction of the robot mechanism 2 (the direction perpendicular to the paper surface in fig. 4). In addition, all of the four finger parts 21 have the same structure and the same length. However, the movement of each finger part 21 is independently controlled.

As shown in fig. 3, each finger part 21 has: a first finger link portion 211, a second finger link portion 212, and a base end portion 213. The base end 213 of the finger part 21 is connected to the base part 20. Here, the base end portion 213 is connected to the base portion 20 so as to be rotatable about an axis in the longitudinal direction of the finger portion 21 (a direction perpendicular to the paper surface in fig. 4) as indicated by an arrow in fig. 4. Further, one end of the second link portion 212 is connected to the base end portion 213 of the finger portion 21. A second joint portion 23 is formed at a connection portion between the second link portion 212 and the base end portion 213. A motor for driving the base end portion 213 to rotate and a motor for driving the second link portion 212 to rotate relative to the base end portion 213 are provided inside the base portion 20. With such a configuration, the drive base end 213 rotates, and accordingly, the finger part 21 is driven to rotate as a whole within a range shown by an arrow in fig. 4. In addition, as shown in fig. 5, the second joint portion 23 is formed so as to be bendable and stretchable.

As shown in fig. 3, 5, and 6, one end of the first finger link portion 211 is connected to the other end of the second finger link portion 212 of the finger portion 21. A first joint portion 22 is formed at a connection portion between the first finger link portion 211 and the second finger link portion 212. A motor for driving the first link portion 211 to rotate relative to the second link portion 212 is provided inside the second link portion 212. With such a configuration, the first joint section 22 is formed so as to be bendable and stretchable, as shown in fig. 6.

In addition, as shown in fig. 3, in the present embodiment, the pressure-sensitive sensor 70 is provided on the front end side of the first finger link portion 211 of the finger portion 21. The pressure sensitive sensor 70 is a sensor that detects an external force (pressure) acting on the distal end portion of the first finger link portion 211.

(base part)

Next, the configuration of the arm control device 42 and the robot control device 43 incorporated in the base unit 4 will be described with reference to fig. 7. The arm control device 42 is a control device for controlling the arm mechanism 3 of the gripping system 1. The hand control device 43 is a control device for controlling the hand mechanism 2 of the gripping system 1. Fig. 7 is a block diagram showing functional units included in the arm control device 42 and the robot control device 43.

The arm control device 42 includes a plurality of drivers that generate drive signals for driving the motors provided in the respective joint portions of the arm mechanism 3, and is configured to supply the drive signals from the respective drivers to the respective corresponding motors. The arm control device 42 includes a computer having an arithmetic processing device and a memory. The arm control device 42 includes an arm control unit 420 and a motor state quantity acquisition unit 421 as functional units. These functional units are formed by executing a predetermined control program on a computer included in the arm control device 42.

The arm control unit 420 supplies a drive signal from each actuator based on object information acquired by an object information acquisition unit 430 described later, which is a functional unit included in the robot control device 43, and controls motors provided in the

joint units

30a, 30b, 30c, 30d, 30e, and 30f of the arm mechanism 3. The arm control unit 420 controls the motors to move the arm mechanism 3, thereby moving the position of the robot mechanism 2 to a desired position (a position at which the object 10 can be gripped by the robot mechanism 2). Further, the motors provided in the

joint portions

30a, 30b, 30c, 30d, 30e, and 30f of the arm mechanism 3 are provided with encoders (not shown) for detecting state quantities (the rotational position, the rotational speed, and the like of the rotary shaft of the motor) relating to the respective rotational states. The state quantity of each motor detected by the encoder of each motor is input to the motor state quantity acquisition unit 421 of the arm control device 42. The arm control unit 420 servo-controls the motors so that the manipulator mechanism 2 moves to a desired position based on the state quantities of the motors input to the motor state quantity acquisition unit 421.

The robot control device 43 includes a plurality of drivers that generate drive signals for driving the motors provided in the robot mechanism 2, and is configured to supply the drive signals from the drivers to the corresponding motors. The robot control device 43 includes a computer having an arithmetic processing device and a memory. The robot control device 43 includes, as functional units, an object information acquiring unit 430, a robot control unit 431, a motor state quantity acquiring unit 432, and a sensor information acquiring unit 433. These functional units are formed by executing a predetermined control program on a computer included in the manipulator control device 43.

The object information acquiring unit 430 acquires object information, which is information on an object to be gripped by the robot mechanism 2. The object information includes information on the type, shape, size, and position of the object, and environmental information around the object (information on objects other than the object existing around the object, for example, information on the shape of a container in which the object is stored, and the arrangement of the objects in the container). The object information acquiring unit 430 may acquire object information input by the user. In addition, when a visual sensor for capturing an image including the object is provided, the object information acquiring unit 430 may acquire the object information from the image captured by the visual sensor.

The robot control unit 431 supplies a drive signal from each driver based on the object information acquired by the object information acquisition unit 430, and controls each motor that drives each finger portion 21 of the robot mechanism 2. Thereby, the object 10 is gripped by the plurality of finger parts 21 of the robot mechanism 2. Each motor of the manipulator mechanism 2 is provided with an encoder (not shown) for detecting a state quantity (a rotational position, a rotational speed, etc. of a rotary shaft of the motor) associated with each rotational state. The state quantity of each motor detected by the encoder of each motor is input to the motor state quantity acquisition unit 432 of the robot control device 43. The hand control unit 431 servo-controls the motors of the respective finger parts 21 so that the plurality of finger parts 21 grip the object, based on the state quantities of the motors input to the motor state quantity acquisition unit 432.

The robot control device 43 also includes a sensor information acquisition unit 433. The detection value of the pressure sensitive sensor 70 provided in the first link portion 211 of each finger portion 21 of the manipulator mechanism 2 is input to the sensor information acquisition portion 433. When the pressure-sensitive sensors 70 detect contact of the finger parts 21 with the object, the robot control unit 431 can control the motors of the finger parts 21 based on the detection signals.

In fig. 7, the arm control device 42 and the hand control device 43 are shown separately as control devices included in the gripping system, but as another method, a configuration may be adopted in which each functional unit is formed in one control device in which two devices are integrated. Even when the control devices included in the gripping system are distinguished as the arm control device 42 and the robot control device 43, each of the functional units shown in fig. 7 may be formed in substantially any control device as long as no technical conflict occurs, and appropriate transmission and reception of information between the arm control device 42 and the robot control device 43 can be performed as necessary. Further, a configuration may be adopted in which a part of each functional unit in the arm control device 42 or the robot control device 43 is formed in a control device separate from the arm control device 42 and the robot control device 43.

(holding object)

In the gripping system 1 of the present embodiment, the object 10 to be gripped may be a bag-like object in which a fluid (gas or liquid) is sealed. As the bag-like object 10 in which gas is sealed, a bag in which snack foods such as potato chips and popcorn are filled can be exemplified. Examples of the bag-like object 10 in which liquid is sealed include a bag in which pickled vegetables are placed and a bag in which liquid detergent is placed. When the fluid-filled baggy object 10 is to be gripped by the robot mechanism 2, the shape of the baggy object 10 is likely to change when pressed by a finger 21 for gripping (hereinafter, sometimes referred to as a gripping finger). When the bag-shaped object 10 is deformed by the pressing of the gripping finger parts, the reaction force of the gripping finger parts from the bag-shaped object 10 is reduced. As a result, if it is difficult to secure sufficient frictional force between the gripping finger parts and the bag-shaped object, it may be difficult to maintain the state in which the bag-shaped object 10 is sandwiched between the gripping finger parts.

(pressing action)

Therefore, in the present embodiment, when the fluid-filled bag-shaped object 10 is gripped by the hand mechanism 2, the pressing operation for bringing the distal end portion of the finger portion 21 of the hand mechanism 2 into contact with the bag-shaped object 10 and pressing the bag-shaped object 10 is performed before the gripping operation, which is an operation for sandwiching the bag-shaped object by the gripping finger portion, is performed. When such a pushing operation is performed, the bag-shaped object 10 is deformed, and therefore the internal pressure of the bag-shaped object 10 can be increased. Further, if the internal pressure of the bag-shaped object 10 is sufficiently increased by performing the press-in operation, the shape of the bag-shaped object 10 is less likely to change even if the bag-shaped object is pressed by the gripping finger parts during the gripping operation. As a result, a sufficient reaction force acts on the gripping fingers from the bag-like object 10. Therefore, a sufficient frictional force for gripping can be ensured between the gripping finger parts and the bag-like object 10.

The details of the press-fitting operation according to the present embodiment will be described below with reference to fig. 8 and 9. Here, the pushing operation is performed with two

finger parts

21A, 21C of the four finger parts 21 of the robot mechanism 2 as pushing finger parts. The pushing operation is realized by controlling the arm mechanism 3 by the arm control unit 420 of the arm control device 42 and controlling the robot mechanism 2 by the robot control unit 431 of the robot control device 43. Fig. 8 is a diagram showing the form of the robot mechanism 2 when the pushing operation is performed using the

finger parts

21A, 21C. However, in fig. 8, the finger part 21B is not shown for convenience. The hollow arrow in fig. 8 indicates the direction of pressing into the bag-like object 10. The arm control unit 420 controls the arm mechanism 3 to move the hand mechanism 2 to a position suitable for the pushing operation by the

finger portions

21A and 21C. That is, the arm control unit 420 moves the robot mechanism 2 in the pushing direction to move the robot mechanism 2 to a position where the distal end portions of the

finger portions

21A and 21C can contact the bag-like object 10. Further, the hand control unit 431 controls the form of each finger portion 21 so that the distal end portions of the pushing

finger portions

21A and 21C can be brought into contact with the bag-like object 10. At this time, the distance d between the distal ends of the pushing

fingers

21A and 21C is set to be equal to or greater than a predetermined distance.

In the present embodiment, as shown in fig. 8, the heights h of the distal end portions of the pushing

finger parts

21A and 21C with respect to the plane perpendicular to the pushing direction are made equal. This makes it easy to bring the distal end portions of the

pressing finger parts

21A and 21C into contact with the bag-shaped object 10. Further, the distal ends of the press-fitting

finger parts

21A and 21C can be equally press-fitted into the bag-like object 10. However, the heights of the distal end portions of the pushing

finger parts

21A and 21C with respect to a plane perpendicular to the pushing direction do not have to be the same. That is, in the pushing operation, the distal end portions of the pushing

finger parts

21A and 21B may be arranged so as to be in contact with the bag-like object 10.

The height of the distal end portions of the

finger parts

21B and 21D, which are not used for the pushing operation, is higher than the height h with respect to a plane perpendicular to the pushing direction. By disposing the distal end portions of the finger parts 21 in this manner, only the distal end portions of the press-fitting

finger parts

21A and 21C can be brought into contact with the bag-like object 10 during the press-fitting operation. However, if only the distal ends of the pushing

finger parts

21A and 21C can be placed in contact with the bag-like object 10, the heights of the distal ends of the

finger parts

21B and 21D, which are not used for the pushing operation, with respect to the plane perpendicular to the pushing direction may be lower than the heights of the pushing

finger parts

21A and 21C.

The control for realizing the above-described pushing operation is executed based on the object information including the information on the type, shape, size, and position of the object of the bag-shaped object 10 acquired by the object information acquiring unit 430. The pressing position of the pressing finger part and the pressing direction of the pressing finger part in the bag-like object 10 may be determined by the user as appropriate. The robot control unit 431 and the arm control unit 420 may determine the pressing position and the pressing direction based on the object information acquired by the object information acquiring unit 430. The press-fit finger part is not limited to the

finger parts

21A and 21C, and may be a combination of other finger parts 21. After completing the control for realizing the position and the form of the manipulator mechanism 2 shown in fig. 8, the arm control unit 420 controls the arm mechanism 3 to move the manipulator mechanism 2 in the direction of the outlined arrow shown in fig. 8, thereby starting the pushing operation.

Fig. 9 is a diagram showing the robot mechanism 2 and the bag-like object 10 when the pushing operation is performed on the bag-like object 10 by the pushing

fingers

21A and 21C. In fig. 9, the hollow arrow indicates the direction of pressing into the bag-like object 10. When the pushing operation is started, first, the distal ends of the pushing

fingers

21A and 21C contact the bag-shaped object 10. Then, the press-fitting operation of pressing in the direction of the hollow arrow in fig. 9 is further continued. This deforms the bag-shaped object 10, and the internal pressure of the bag-shaped object 10 increases accordingly. Then, as the amount of press-fitting of the

finger parts

21A and 21C into the bag-like object 10 during the press-fitting operation increases, the internal pressure of the bag-like object 10 increases. Here, the pushing amount may be defined as a displacement amount of the distal end portions of the pushing

finger parts

21A and 21C in the pushing direction (the direction of the hollow arrow in fig. 9) from the position where the distal end portions of the pushing

finger parts

21A and 21C contact the bag-shaped object 10 after the pushing operation is started. The broken line in fig. 9 shows the bag-like object 10 when the

finger parts

21A and 21C are in contact with the bag-like object 10. In fig. 9, the pushing amount of the pushing

fingers

21A and 21C during the pushing operation is denoted by L.

At this time, the pressure sensor 70 provided at the distal end portions of the pushing

finger portions

21A and 21C detects the pressure applied from the bag-shaped object 10. Therefore, when the internal pressure of the bag-like object 10 increases as the amount of pushing the pushing

fingers

21A and 21C into the bag-like object 10 increases, the pressure detected by the pressure-sensitive sensors 70 provided at the distal ends of the pushing

fingers

21A and 21C also increases. The sensor information acquiring unit 433 acquires the pressures detected by the pressure-sensitive sensors 70 provided in the respective press-fitting

finger sections

21A and 21C as independent values. When any of the pressures detected by the pressure-sensitive sensors 70 provided in the respective press-fitting

finger parts

21A and 21C acquired by the sensor information acquiring unit 433 becomes equal to or higher than a predetermined pressure, the arm control unit 420 stops the driving of the arm mechanism 3 for moving the robot mechanism 2 in the direction of the outlined arrow in fig. 9. This stops the pushing operation of the bag-shaped object 10. Here, the predetermined pressure is a pressure that can ensure sufficient friction between the gripping fingers for gripping and the bag-shaped object 10 in the gripping operation described later to achieve gripping of the object. The predetermined pressure may be appropriately determined by the user based on experiments or the like. The sensor information acquiring unit 433 may determine the position based on the object information acquired by the object information acquiring unit 430. During the pushing operation, the hand control unit 431 performs servo control of the motors of the pushing

finger parts

21A and 21C so as not to change the positions of the distal end parts of the pushing

finger parts

21A and 21C on the hand mechanism 2. In addition, in the present embodiment, the pressure-sensitive sensors 70 are provided to all the finger portions 21 of the manipulator mechanism 2. However, in order to realize the press-fitting operation, the pressure-sensitive sensor 70 may be provided at least at the distal end portions of the finger portions (in the present embodiment, the

finger portions

21A and 21C) serving as the press-fitting finger portions. If the pressure-sensitive sensor 70 is provided at the distal end of the pushing finger part, it can be determined whether or not the internal pressure of the bag-shaped object 10 has increased to such an extent that the gripping operation can be performed.

(holding action)

Next, the details of the gripping operation according to the present embodiment will be described with reference to fig. 10. Fig. 10 is a diagram showing the robot mechanism 2 and the bag-like object 10 when the gripping operation is performed using the

finger parts

21A and 21C serving as the pushing finger parts during the pushing operation as the gripping finger parts. In the present embodiment, the gripping operation is executed after the pushing operation is stopped. At this time, the gripping operation is performed while maintaining the state in which the

pressing fingers

21A and 21C press-fit the bag-like object 10 when the pressing operation is stopped. More specifically, as shown in fig. 10, the robot control unit 431 uses the

finger parts

21A and 21C serving as the pressing-in finger parts as the gripping finger parts, and bends the first joint parts 22A and 22C while maintaining the state in which the

gripping finger parts

21A and 21C are pressed into the bag-like object 10 (in fig. 10, the arrows indicate the directions in which the first joint parts 22A and 22C of the

respective finger parts

21A and 21C are bent). Thus, the distance between the distal ends of the

gripping finger parts

21A and 21C is shortened, thereby realizing the gripping operation, which is an operation of sandwiching the bag-like object 10 between the

gripping finger parts

21A and 21C. In this case, the hand control unit 431 may perform the gripping operation by bending the second joint portions 23A and 23C of the

gripping finger parts

21A and 21C, respectively. Here, even if the first joint portions 22A and 22C and/or the second joint portions 23A and 23C of the

gripping finger portions

21A and 21C are bent, the amount of pressing in the bag-like object 10 by the distal end portions of the

respective finger portions

21A and 21C at the time of stopping the pressing operation (pressing amount L in fig. 9) can be maintained. Therefore, a sufficient reaction force acts from the bag-like object 10 to the

gripping finger parts

21A and 21C. Therefore, a friction force sufficient for gripping the bag-shaped object 10 is generated between the

gripping finger parts

21A and 21C and the bag-shaped object 10. Therefore, the bag-like object 10 is easily maintained in the state of being sandwiched between the

gripping finger parts

21A and 21C. As a result, the bag-like object 10 can be stably gripped by the robot mechanism 2.

< control flow >

Next, a control flow of the gripping system in the case of performing gripping of the bag-like object 10 according to the present embodiment will be described based on the flowchart shown in fig. 11. The control flow is realized by executing a predetermined control program in the arm control unit 420 of the arm control device 42 and the hand control unit 431 of the hand control device 43.

In this flow, first, in S101, the position and the form of the manipulator mechanism 2 for performing the pushing operation are determined based on the object information on the bag-shaped object 10 acquired by the object information acquiring unit 430. Next, in S102, the position and the form of the robot mechanism 2 are controlled to the position and the form determined in S101. Thus, in the present embodiment, the position and the form of the robot mechanism 2 for performing the pushing operation are realized as shown in fig. 8.

Next, in S103, the pushing operation is started. That is, the movement of the robot mechanism 2 in the pushing direction (the direction of the outlined arrow in fig. 8 and 9) in the form of the pushing action is started. As described above, during the pushing operation, the distal ends of the

finger portions

21A and 21C of the robot mechanism 2 are brought into contact with the bag-shaped object 10 and then pushed into the bag-shaped object 10. Next, in S104, it is determined whether or not any of the pressures P1 and P2 detected by the pressure sensors 70 provided in the respective pushing

fingers

21A and 21C, which are acquired by the sensor information acquiring unit 433, has reached a predetermined pressure Pn or more. When a negative determination is made in S104, the process of S104 is executed again. In this case, the pushing operation is continued. That is, the movement of the robot mechanism 2 in the pushing direction is continued. Therefore, the amount of pushing the bag-like object 10 by the distal end portions of the

finger portions

21A and 21C of the robot mechanism 2 increases.

On the other hand, if an affirmative determination is made in S104, then the pushing operation is stopped in S105. That is, the movement of the robot mechanism 2 in the pushing direction is stopped. Then, the position of the robot mechanism 2 is maintained at the time point when the pushing operation is stopped. When the push operation is stopped in S105, the process of S106 is executed. In S106, the gripping operation by the gripping

finger parts

21A and 21C is started. Thus, the bag-like object 10 is sandwiched by the

finger parts

21A, 21C while the state in which the distal end parts of the

finger parts

21A, 21C of the robot mechanism 2 are pushed into the bag-like object 10 is maintained.

In the present embodiment, the gripping operation by the gripping

finger parts

21A, 21C is started after the pushing operation by the pushing

finger parts

21A, 21C is stopped. However, when any one of the pressures detected by the pressure-sensitive sensors 70 provided in the pushing

fingers

21A and 21C reaches a predetermined pressure or more due to the pushing operation, the gripping operation may be started while continuing the pushing operation.

(modification 1)

In the above embodiment, the two

finger parts

21A and 21C are used as the pushing finger parts. However, the press-fitting finger portions are not limited to two. That is, four finger portions 21 or three finger portions 21 in the robot mechanism 2 may be used as the pushing finger portions. In this case, as in the above-described embodiment, the pushing operation is performed with the distal end portions of the respective pushing finger portions spaced apart from each other by a predetermined distance. Even when four finger portions 21 or three finger portions 21 in the robot mechanism 2 are used as the pushing finger portions, the pressure-sensitive sensors 70 are provided at least at the distal end portions of the respective finger portions 21 used as the pushing finger portions. Even when four finger parts 21 or three finger parts 21 in the robot mechanism 2 are used as the pushing-in finger parts, the respective finger parts 21 used as the pushing-in finger parts can be used as the gripping finger parts to perform the gripping operation. Note that the number of press-in fingers may be determined by the user as appropriate. The number of press-fitting finger parts may be determined by the hand control unit 431 based on the object information acquired by the object information acquisition unit 430.

(modification 2)

Further, if at least two finger parts 21 of the robot mechanism 2 are used for the gripping operation, the bag-like object 10 can be gripped. Therefore, it is not always necessary to use all the finger parts 21 serving as the pushing finger parts as the gripping finger parts. That is, when the three finger parts 21 in the robot mechanism 2 are used as the pushing finger parts, two of the three pushing finger parts may be used as the gripping finger parts to perform the gripping operation. In addition, when the four finger parts 21 in the robot mechanism 2 are used as the pushing finger parts, two or three of the four pushing finger parts may be used as the gripping finger parts to perform the gripping operation. However, in these cases, the gripping operation by the gripping finger parts is executed while the tip end parts of the plurality of pressing finger parts are pressed into the bag-like object 10. In addition, a finger part 21 different from the finger part 21 used as the pushing finger part may be used as the gripping finger part.

< example 2 >

The schematic configuration of the gripping system of the present embodiment is the same as that of embodiment 1 described above. In the present embodiment, a part of the four finger portions 21 of the robot mechanism 2 is used as a press-in finger portion to perform a press-in operation. Then, the gripping operation is performed using the finger part 21 not used as the pushing finger part among the four finger parts 21 of the robot mechanism 2. An example in which two of the

finger parts

21A, 21C of the robot mechanism 2 are used as the pushing finger parts and the other two

finger parts

21B, 21D are used as the gripping finger parts will be described below with reference to fig. 12. Fig. 12 is a diagram for explaining the pushing operation and the gripping operation in the present embodiment.

In the present embodiment, as in the case shown in fig. 8 and 9 in embodiment 1, the

finger parts

21A and 21C in the robot mechanism 2 are used as the pushing finger parts to perform the pushing operation. In the present embodiment, the distance between the distal ends of the press-fitting

finger parts

21A and 21C is also a predetermined distance or more. In the present embodiment, as shown in fig. 12, the

finger parts

21B and 21D not used as the pushing finger parts are controlled so as not to contact the bag-like object 10 during the pushing operation. When any one of the pressures detected by the pressure-sensitive sensors 70 provided in the respective press-fitting

finger parts

21A and 21C reaches a predetermined pressure or more, the press-fitting operation is stopped.

When the pushing operation is stopped, the gripping operation is performed using the

finger parts

21B and 21D not used as the pushing finger parts as the gripping finger parts. At this time, the gripping operation is performed while maintaining the state in which the pushing

fingers

21A and 21C are pushed into the bag-like object 10 when the pushing operation is stopped. The robot control unit 431 drives the joints of the

gripping finger parts

21B and 21D in the direction in which the bag-like object 10 is sandwiched between the

gripping finger parts

21B and 21D to perform a gripping operation (in fig. 12, arrows indicate the driving directions of the joints of the

gripping finger parts

21B and 21D). During the gripping operation, the hand control unit 431 performs servo control of the motors of the respective pushing

finger parts

21A and 21C so as not to change the positions of the pushing

finger parts

21A and 21C.

As described above, in the present embodiment, the bag-like object 10 is sandwiched by the gripping

finger parts

21B and 21D while the state in which the distal end parts of the press-in

finger parts

21A and 21C are press-fitted into the bag-like object 10 is maintained. Therefore, a sufficient reaction force acts from the bag-like object 10 to the gripping

fingers

21B and 21D. Therefore, a friction force sufficient for gripping the bag-shaped object 10 is generated between the

gripping finger parts

21B and 21D and the bag-shaped object 10. Therefore, the bag-like object 10 is easily maintained in the sandwiched state between the

gripping finger parts

21B and 21D. As a result, the bag-like object 10 can be stably gripped by the robot mechanism 2.

However, as in example 2, when the gripping operation is performed by the gripping

finger parts

21B and 21D different from the pushing

finger parts

21A and 21C, the gripping

finger parts

21B and 21D are brought into contact with the bag-shaped object 10 after the pushing operation is stopped, and then the bag-shaped object 10 is sandwiched by the gripping

finger parts

21B and 21D. In contrast, as in example 1, when the gripping operation is performed using the pushing fingers as the gripping fingers, the gripping fingers are already in contact with the bag-shaped object 10 at the time when the pushing operation is stopped. Therefore, immediately after the pushing operation is stopped, the bag-like object can be sandwiched by the gripping finger portions. Therefore, when the gripping operation is performed using the pushing fingers as the gripping fingers as in example 1, the tact time for gripping the bag-like object 10 can be shortened as compared with the case of performing the gripping operation using gripping fingers different from the pushing fingers as in example 2.

In the present embodiment, after the pushing operation by the pushing

fingers

21A and 21C is stopped, the gripping operation by the gripping

fingers

21B and 21D is started. However, when any one of the pressures detected by the pressure-sensitive sensors 70 provided in the pushing

fingers

21A and 21C reaches a predetermined pressure or more due to the pushing operation, the gripping operation may be started while continuing the pushing operation. In the robot mechanism 2, the gripping operation may be performed using the finger parts serving as the pushing finger parts and the finger parts other than the pushing finger parts. However, in this case as well, the gripping operation is performed while maintaining the state in which the finger portion for pushing is pushed into the bag-like object 10.

(modification example)

The pushing operation may be performed using only one finger portion 21 of the robot mechanism 2 as a pushing finger portion. In this case, after the pushing operation by one pushing finger part is started, the pushing operation is stopped when the pressure detected by the pressure-sensitive sensor 70 provided in the pushing finger part becomes equal to or higher than a predetermined pressure. Then, while maintaining the state in which one pressing finger portion is pressed into the bag-like object 10, the gripping operation by the gripping finger portion is executed.

However, in the case where only one pressing finger part is provided, the amount of pressing of the bag-like object 10 by the pressing finger part during the pressing operation becomes larger than in the case where a plurality of pressing finger parts are provided. In other words, as illustrated in fig. 8, 9, or 12, when the pushing operation is performed with at least two fingers used as pushing finger portions and with the distance between the distal end portions of the pushing finger portions being equal to or greater than a predetermined distance, the amount of pushing of the bag-shaped object 10 by the pushing finger portions when the internal pressure of the bag-shaped object 10 is increased by the same degree can be reduced as compared with the case of pushing operation by one pushing finger portion. That is, the amount of pressing the bag-like object 10 by the pressing finger portion when the pressing operation is stopped can be further reduced. By reducing the amount of pressing the bag-like object by the finger part for pressing in, it is possible to suppress damage to the contents of the bag-like object 10 due to the pressing operation. Further, by reducing the amount of pressing the bag-like object 10 by the pressing fingers, the time taken from the start of the pressing operation to the start of the gripping operation can be shortened. As a result, the tact time for gripping the bag-like object can be shortened.

Description of reference numerals:

1 … handling the system; 2 … robot mechanism; 20 … a base portion; 21 … finger parts; 22 … first joint portion; 23 … second joint part; 211 … a first finger link portion; 212 … second finger link portion; 213 … base end portion; 3 … arm mechanism; 30a … first joint part; 30b … second joint part; 30c … third joint part; 30d … fourth joint part; 30e … fifth joint part; 30f … sixth joint part; 31 … first arm link part; 32 … second arm link portion; 33 … third arm link portion; 34 … fourth arm link portion; 35 … fifth arm link portion; 36 … a connecting member; 4 … base part; 42 … arm control; 420 … arm control; 421 … motor state quantity acquisition unit; 43 … robot control; 430 … an object information acquiring unit; 431 … robot control part; 432 … motor state quantity acquisition unit; 433 … a sensor information acquisition unit; 70 … pressure sensitive sensor.

Claims

1. A gripping system is provided with: a robot mechanism configured to grip an object with a plurality of finger portions; and a control device for controlling the manipulator mechanism when gripping the object, wherein,

when the object is a bag-shaped object in which a fluid is sealed, at least one of the plurality of finger parts of the robot mechanism is a press-in finger part,

a pressure detection unit is provided at a tip of a finger portion serving as the press-in finger portion in the robot mechanism,

when the object is the bag-shaped object, the control device causes the distal end portion of the press-in finger portion of the manipulator mechanism to come into contact with the bag-shaped object to press-fit the bag-shaped object, and then executes a gripping operation, which is an operation of gripping the bag-shaped object with at least two of the plurality of finger portions in a state where the press-in finger portion is pressed into the bag-shaped object, after the pressure detected by the pressure detection portion provided in one of the press-in finger portions has reached a predetermined pressure or more, or after any one of the pressures detected by the pressure detection portions provided in the respective press-in finger portions has reached a predetermined pressure or more.

2. The handling system of claim 1, wherein the handle is configured to be coupled to a handle of a hand-held device

The control device presses the bag-shaped object into the press-in finger parts by bringing the distal end portions of the press-in finger parts into contact with the bag-shaped object in a state where the distance between the distal end portions of the press-in finger parts is equal to or greater than a predetermined distance.

3. The handling system of claim 1 or 2,

the control device executes the gripping operation using the pushing finger part while maintaining a state in which the pushing finger part is pushed into the bag-shaped object.

4. The handling system of any one of claims 1-3, wherein,

when the press-in finger parts are at least two finger parts, the control device presses the bag-shaped object by bringing the distal end portions of the press-in finger parts into contact with the bag-shaped object in a state where the distal end portions of the press-in finger parts are at the same height with respect to a plane perpendicular to the press-in direction of the press-in finger parts.

5. A gripping method for gripping an object by a robot mechanism having a plurality of finger parts,

in the robot mechanism, a pressure detection unit is provided at a tip end portion of the finger portion serving as the press-in finger portion,

the holding method comprises the following steps:

pressing the bag-shaped object by bringing the tip of the pressing finger part into contact with the bag-shaped object when the object is the bag-shaped object; and

and a gripping operation of gripping the bag-shaped object with at least two of the plurality of finger portions in a state in which the pressing-in finger portion is pressed into the bag-shaped object, after any one of the pressure detected by the pressure detecting portion provided in one of the pressing-in finger portions or the pressure detected by the pressure detecting portion provided in each of the pressing-in finger portions reaches a predetermined pressure or more.